Quick, Fast & Lively

Words for quick, fast and lively in Celtic languages.

Old Irish (Goídelc) mer = crazy
Irish (Gaeilge) mear [mʲaɾˠ] = quick, fast, nimble, lively, spirited; precipitate, hasty, rash; quick-tempered, fiery; mad, crazy; furious, raging, angry
Scottish Gaelic (Gàidhlig) mear [mɛr] = merry, joyful; frisky, lively
Manx (Gaelg) merre [mɛr] = frenzy
Welsh (Cymraeg) miri = merry, gay; fun, merriment, mirth; tumult, fuss, bother, predicament

Etymology
Possibly from the Latin meretrix (prostitute), from mereō (merit, deserve) &‎ -trīx (feminine noun suffix) = “she who earns”.

Sources: Wiktionary, Am Faclair Beag, Online Manx Dictionary, Teanglann.ie, Geiriadur Prifysgol Cymru, McBain’s Dictionary, In Dúil Bélrai

Bad

Words for bad in Celtic languages.

Proto-Celtic *drukos = bad
Old Irish (Goídelc) droch [drox] = bad
Irish (Gaeilge) droch [drɔx] = bad, poor, evil
Scottish Gaelic (Gàidhlig) droch [drɔx] = bad, evil, wicked
Manx (Gaelg) drogh = evil, wicked, bad, abusive, unenviable, misfortune, badness
Proto-Brythonic *drug = bad
Welsh (Cymraeg) drwg [druːɡ] = bad, rotten, putrid; poor, piteous, wretched; sorry, grievous, sad; unfavourable, causing disquiet; injurious, harmful; unpleasant (taste); indecent, obscene (words); counterfeit, false; bad; harsh, cruel, severe, ruthless
Cornish (Kernewek) drog [drɔ:g / dro:g] = bad, evil, invalid, naughty, wicked, nasty
Breton (Brezhoneg) drouk = bad

Etymology
Possibly from the Proto-Indo-European *dʰrewgʰ- (to deceive).

Words marked with a * are reconstructions.

Sources: Wiktionary, Am Faclair Beag, Online Manx Dictionary, Teanglann.ie, Geiriadur Prifysgol Cymru, Gerlyver Kernewek, Dictionnaire Favereau